STUDY OF THE FLORISTIC COMPOSITION OF FIR-SPRUCE-BEECH FORESTS IN SERBIA AND BOSNIA-HERZEGOVINA

The mixed forest of fir, spruce, and beech (Piceo-Abietetum Čolić 1965) is an important and widespread plant community on the Balkan Peninsula. Within the Dinarides, it occupies the upper zone of the beech-fir forest belt, establishing a regional belt of vegetation in the Illyrian province. This community occupies significant areas in western and southwestern Serbia where it also creates a regional belt, thus confirming that this part of Serbia belongs to the Illyrian floral-geographical province. This paper compares the floristic composition of the fir-spruce-beech forests in Serbia and Bosnia-Herzegovina in order to determine the differences between the study stands. A total of 29 relevés were analyzed, 17 from the mountain of Lisina (Bosnia-Herzegovina) and 12 from the Pešter plateau (Serbia). Cluster analysis revealed a clear differentiation between the study stands and species in Bosnia-Herzegovina and those in Serbia. The main difference is in the dominant species: Fagus moesiaca (K. Maly) Czecz. in Serbia and Fagus sylvatica L. in Bosnia-Herzegovina. In Bosnia-Herzegovina, the forest grows under conditions of a uniform, maritime and humid climate, while in Serbia it grows under conditions of a continental climate with less rainfall and a strong zoo-anthropogenic impact. Regarding the spectrum of life forms, there are more phanerophytes and geophytes in Bosnia-Herzegovina than in Serbia. On the other hand, the spectrum of floral elements in Serbia is richer in xerophilous, Balkan and sub-Mediterranean floral elements.


INTRODUCTION
The class of frigophilous coniferous forests 1980 and the order Vaccinio-Piceetalia (Pawlowski in Pawlowski et al. 28) Br.-Bl. in Br.-Bl. et al.1939. emend K. Lund 1967.are mainly composed of mountain and alpine communities that can survive in the conditions typical of a cold and humid boreal climate, mainly at altitudes between 1300 and 1900 m.This order, and its corresponding class, also comprises the alliance of acidophilus spruce forests (Vaccinio-Piceion Pawlowski et al. 28) Br.-Bl. in Br.-Bl. et al.1939.)that includes some regional communities.Within the alliance and suballiance Abieti-Piceenion Br.-Bl. in Br.-Bl. et al.1939., forests of fir, spruce and beech (Piceo-Abietetum Čolić 1965) (syn. Piceo-Fago-Abietetum Čolić 1965.; Piceeto-Abieti-Fagetum moesiacum Mišić et al. 1978.; Abieti-Fagetum piceetosum Mišić & B. Jovanović 1983.) are defined as a specific tri-dominant community, which apart from having great economic importance, have played an important role in the historical development of the vegetation of the Balkan Peninsula.
In terms of the historical development of vegetation, the mixed fir, spruce and beech forest is older than the forest of beech and fir, and considering that polydominant forests are the closest ancestors of primeval forests, these forests are testimony to the historical development of vegetation not only in Serbia, but also on the whole of the Balkan Peninsula (Mišić, 1982).
Since the fir-spruce-beech forest builds a regional belt of vegetation both in Bosnia-Herzegovina and in western Serbia and has considerable scientific and practical importance, the aim of this study was to broaden the knowledge about this association and to compare the floristic data in order to determine the differences between the studied forests.This research may eventually help determine the syntaxonomic classification of these forests.

Study area
The research area comprises mixed forests of fir and beech with spruce on the mountain of Lisina (Bosnia-Herzegovina) and on Pešter plateau (Serbia).Lisina mountain (1467 m a.s.l., 44°23'51"N, 17°02'30" E) lies in the inland of the Dinarides in western Bosnia-Herzegovina, i.e. in the southwestern part of the Republic of Srpska entity, in the Bosanska Krajina region.Lisina is about 84 km from the regional center of Banja Luka.The massif extends in a northwest-southeast direction.The area is characterized by a wet perhumid climate.It has a complex geological structure with different geological formations covering a small area (Mudrenović, 1991).According to Eremija et al. (2014), the following types of soil occur over siliceous rocks: ranker, dystric cambisols, luvisols and podzol, whereas rendzina and luvisol occur on limestone and dolomite bedrock.
The Pešter plateau extends over the border zone between the Dinarides and the Rhodopes, within the Stari Vlah-Raška mountain range in southwestern Serbia.It forms its central part with a series of individual, mostly karst, mountains (Rakonjac, 2002).The plateau is surrounded by high mountains that isolate it both from the sea and from the neighboring regional valleys.The mean altitude ranges between 900 and 1200 m, with individual mountains reaching 1700 m a.s.l.Together with Sjenica valley it lies at 43°16.5'N and 20°E.The total area of the plateau is 1058.5 km².The lower part of the plateau is characterized by a temperate continental climate, while an alpine climate prevails in its upper regions.The microclimate of the Pešter plateau is distinguished by temperatures below the normal values and low amounts of total rainfall.The whole plateau has the character of a depression, with a harsh local microclimate.It has a diverse bedrock that produces different types of soil: calcareous black soil, rankers, eutric and dystric cambisol, limestone brown soil, luvisol, pseudogley, fluvisol, and gley soils (Rakonjac, 2002)

Data collection and processing
The study of the floristic composition of the investigated stands was based on 29 relevés (phytocoenological data records).The classical method of the Zurich-Montpellier school of phytocoenology (Braun-Blanquet, 1964).Out of 29 relevés, 17 were sampled in the forest of beech and fir with spruce (Piceo-Abietetum Čolić 1965) on Mt.Lisina, in the southwestern part of the Republic of Srpska (Bosnia-Herzegovina).The data for 12 relevés in the area of Pešter, in southwestern Serbia, were obtained from the relevant literature (Tomić and Rakonjac, 2003).Syntaxonomic names follow Tomić and Rakonjac (2013).The research comprises the analysis of two spectra: the spectrum of floral elements according to the systematization of phytogeographical elements (Gajić, 1980), and the spectrum of life forms (Kojić et al., 1997).
In order to determine similarities in the floristic composition of the study stands, Bray-Curtis cluster analysis (measuring similarity) with the option "Group Average" in BIODIVERSITY PRO (McAleece et al., 1997) was performed.CA vegetation data analysis was performed using the statistical software CANOCO 4.5 (Lepš and Šmilauer, 1999).The coverabundance score obtained for each species within a relevé were transformed using the method of Van Der Maarel (1979).

Floristic composition
The fir-spruce-beech forest in the area of Lisina (Bosnia-Herzegovina) occurs at the altitude of about 1100 FLORISTIC COMPOSITION OF FIR-SPRuCE-BEECH FOREST m a.s.l.It grows on slopes of varying steepness, from mild (3-4°) to very steep (36°), but it is predominantly found on medium-steep slopes with different aspects, east-facing being the most common.Its bedrock is diverse, composed of marly, sometimes dense, limestones, limestones with ammonites, dolomite and siliceous rocks.The soil surface is slightly rocky because the bedrock is subject to the process of physical weathering.The stands on limestone bedrock grow on rendzinas, which usually have an expressed regolith contact that deepens the physiologically active layer of soil.The forests on silicates mainly grow on deep soils (dystric cambisols and luvisols), but can be also found on podzols.The trees in the study stands are characterized by a high technical value and good health.There are 74 taxa recorded in 17 relevés (Table 1).V +-2.2 IV +-1.3 Festuca drymeia M. et K.
IV +.2-3.3III +.The fir-spruce-beech forest in the Pešter region (Serbia) is found at altitudes between 1200 and 1450 m, although most of the stands are found above 1350 m.It occurs on very steep to craggy terrains, with slope steepness ranging from 20° to 40°.The aspect is also varied, but north-and northwest-facing slopes prevail.The association can be found on very different parent materials: at lower altitudes, it occurs on sandstone, shale, chert and marl and at higher altitudes on diabase, limestone with chert, spilite, gabroamphibolite and diabase chert.In the area of Pešter, this association has a mosaic distribution that results from site conditions and zoo-anthropogenic impact that have affected the floristic composition.There are 92 taxa recorded in 12 relevés (Table 1).

Statistical analyses
Cluster analysis (Fig. 1) shows that the study stands make two separate groups: one group is the fir-sprucebeech forest in Serbia and the other is the fir-sprucebeech forest in Bosnia-Herzegovina.There is no overlapping between the study stands, which suggests that there is clear floristic differentiation between them.
CA analysis produced similar results as the cluster analysis.The ordinate system (Fig. 2) shows there are some obvious similarities between the stands of the two investigated sites, but certain differences are also evident.They have a large number of species in common: Abies alba Mill., Asperula odorata L., Rubus idaeus L., Salix caprea L., Prenanthes purpurea L., etc.We manually moved the names of these species within the coordinate system in order to achieve better visibility.It should be noted that Moesian beech (Fagus moesiaca (K.Maly) Czecz.) is the edifying species in Serbia while in Bosnia-Herzegovina it is European beech (Fagus sylvatica L.).
However, a certain grouping of species is evident within the ordinate system, so the phytocoenological relevés from Pešter, among others, include pioneer species Betula pendula Roth.and Populus tremula L. in the layer of trees, shrubs and ground flora, which indicates a certain degree of forest degradation.Daphne blagayana Frey., Astrantia major L., Rosa pendulina L., Melica uniflora Retz., etc. can be specified as species that occur only in Serbia.
The relevés sampled on Mt.Lisina have the groups of species typical of the Fagetalia order: Acer pseudoplatanus L., Fagus sylvatica L., Actaea spicata L., etc., as well as species of the Vaccinio-Piceetalia order: Prenanthes purpurea L., Pyrola secunda L. and others, which indicate a high degree of floristic homogeneity and stability of the study stands.The following species can be marked as important in the firspruce-beech forest of Mt.Lisina: Festuca drymeia M. et K., Asarum europaeum L., Melampyrum silvaticum L., Atropa belladonna L.

Spectrum of life forms
There are marked differences in the spectrum of life forms (Fig. 3 A).Hemicryptophytes are the dominant life form in both Serbia and Bosnia-Herzegovina, but they are more abundant in the forest on the territory of Serbia (54%:41%).They are followed by the group of phanerophytes, which are more common in Bosnia-Herzegovina (31%:21%).Geophytes are slightly more numerous in Bosnia-Herzegovina than in Serbia (20%:14%), while chamaephytes have almost the same share.Therophytes and therophytes/chamaephytes are the rarest, but are more frequent in Serbia.

Spectrum of floral elements
The spectrum of floral elements is in both countries dominated by the collective group of Central-European floral elements, with almost the same abundance (Fig. 3 B).It is followed by a group of species of broad ecological amplitude of the Eurasian distribution type, and by circumpolar species and cosmopolitans.The main difference is in the presence of xerophilous floral elements.The presence of xerophilous floral elements (Mediterranean, Balkan, Balkan-Apennine) is twice as high in the forest in Serbia than in Bosnia-Herzegovina (16%:7%).

DISCUSSION
The mixed forests of fir, spruce and beech (Piceo-Abietetum Čolić 1965) has widespread distribution throughout the Balkan Peninsula, from Mt. Plješevica in Croatia to the Rhodope Mountains in Bulgaria.On the territory of Montenegro, it approaches its southern timberline, where it reflects specific maritime cli-   (Čurović et al., 2011).In the Illyrian province, in the area of the Dinarides, it occupies a higher belt of beech-fir forest zone and reaches an altitude of 1500 m.The community covers vast areas of Bosnia-Herzegovina.In the growing stock of the Republic of Srpska, it accounts for over 45% of the total area of forests with natural regeneration.Its distribution range is beyond the strong impact of Mediterranean and Pannonian climate.In the area of Jadovnik, in western Bosnia-Herzegovina, this community represents the primeval type of vegetation and a regional forest community typical of the altitudinal belt between 1200-1500 m a.s.l.(Bucalo, 1995).
In Serbia, the community is generally treated as a feature of the contact zone between the belts of beech and spruce forests, where it occupies disjunctive areas.On some mountains with a well-developed belt of monodominant spruce forests (Kopaonik, Golija, Stara Planina), the community of fir, spruce and beech occupies broad river valleys with specific maritime climate conditions (Tomić, 2004).Although it has been recorded in several mountain ranges in Serbia, only on Mt.Tara and the Pešter plateau, where there is no clearly expressed belt of monodominant spruce forests, does it create an oroclimatogenic belt similar to that in Bosnia.The existence of this belt supports the statement that western and southwestern Serbia belongs to the Illyrian floral-geographical province, as confirmed by earlier studies (Janković, 1984).
Due to its similarity in floristic composition with Abieti-Fagetum forests (in the area where the spruce grows), the fir, spruce and beech forest was generally considered its variant (Mišić and Jovanović, 1983), and hence rarely studied, especially in Serbia.Čolić (1964) first noted the broad distribution of beech, fir and spruce forest, stressing its regional character on Mt.Tara, described in more detail in subsequent studies that differentiated several subassociations (Cvjetićanin and Novaković, 2010), and the authors stated that this was the most common plant community in the study area.Large areas are also covered by the community on Mt.Zlatar (Obratov, 1992), and on Pešter (Tomić and Rakonjac, 2003), where the authors point to its zonal (regional) character.
The spectrum of life forms in Bosnia-Herzegovina has a greater number of phanerophytes than the one in Serbia.Since the species belonging to this life form neither grow in extremely cold nor extremely dry areas (Diklić, 1984), it can be concluded that the forest in Bosnia-Herzegovina grows in conditions of a more maritime, humid and uniform climate compared to that in Serbia.The dominance of hemicryptophytes on Pešter indicates the kind of climate typical of temperate and cold regions to which the studied area belongs.
There are also some differences in the spectrum of floral elements between the study stands, which are primarily due to different climatic influences.Pešter (Serbia) has a higher percentage of xerophilous (primarily sub-Mediterranean and Balkan) floral elements, which is a result of lower amounts of rainfall at this site.If we compare the amount of rainfall of the study sites at an altitude of 1300 m, we can see that it amounts to 1464 mm on Mt.Lisina (Eremija, 2010) and 922.7 mm on Pešter (Rakonjac, 2002).Lisina has a transitional pluviometric regime − between maritime and continental, while a continental regime prevails on Pešter, although with a strong maritime effect.Both localities are characterized by the strong presence of frigophilous species (floral elements of northern regions and circumpolar species), which can withstand low temperatures and high altitudes.
From the above it can be concluded that the beech, fir and spruce forests of Serbia and Bosnia-Herzegovina have a lot in common regarding their floristic composition.However, there are some differences as well, the greatest being dominant species.Fagus moesiaca (K.Maly) Czecz. is dominant in Serbia and Fagus sylvatica L. in Bosnia-Herzegovina.In Bosnia-Herzegovina, the forest grows in conditions of a uniform, maritime and humid climate, while in Serbia it grows in conditions of a continental climate with a smaller amount of rainfall.
Author's contributions: Saša Eremija and Rade Cvjetićanin -collection and data analysis, coordinating and setting the goal of the research.Marijana Novaković-Vuković − statistical analysis of data and study design.Ljubinko Rakonjac, Snežana Stajić, Aleksandar Lučić and Zoran Miletić -collection and data analysis.
Conflict of interest disclosure: All authors of the present paper confirm no actual or potential conflicts of interest, including any financial, personal, or other relationships with people or organizations.

Fig. 1 .
Fig. 1.Cluster analysis of fir, spruce and beech stands in Serbia and Bosnia and Herzegovina

Fig. 3
Fig.3 Spectrum of life forms and spectrum of floral elements in fir-spruce-beech forests in Serbia and Bosnia and Herzegovina